Glow switch



Jan. 18, 1949. s. H. NOBLE GLOW SWITCH Filed May 1, 1947 I I-i lnvervbor: Sidney H. Noble,

Patented Jan. 18, 1949 GLOW swrrcn Sidney Howard Noble, Harrow Weald, England,

assignor to General Electric Company, a corporation of New York Application May 1, 1947, Serial No. 745,329 In Great Britain May 13, 1946 5 Claims. 1

This invention relates to glow starter switches for electric discharge lamps. A glow starter switch comprises a discharge tube for connection between the lamp electrodes and in which a glow discharge heats a bimetallic strip which is thus caused to bend and close contacts. The closure of the contacts causes the glow discharge to cease so that the contacts open, thereby breaking a circuit containing reactance. The resulting voltage surge causes a discharge in the lamp to start.

Since, when the glow discharge ceases, the bimetallic strip cools relatively slowly, the contacts open relatively slowly and there is a tendency for the contacts to chatter, which may cause flickering of the lamp during starting.

It is an object of the present invention to provide a glow starter switch which is'more positive in operation and less liable to suffer from chattering than known switches of this kind.

According to the present invention, a glow starter switch has one of its contacts mounted upon a member which is slidably mounted and which is coupled to the bimetallic strip by a lost motion coupling. The arrangement is such that after the bimetallic strip has been heated and has displaced the slidable member to bring its contact into engagement with a second contact, and as the bimetallic strip then cools, it first moves freely without separating the contacts owing to the lost motion coupling, and on emgaging the slidable member forces the contacts apart more rapidly and positively than with known glow starter switches.

Other features and advantages of the invention will be apparent from the following detailed description of one embodiment thereof, which is given by way of example.

In the drawing, Figs. 1 and 2 are side and front elevations, respectively, of a glow switch comprising my invention; Fig. 3 is a plan view thereof; and Fig. 4 is a diagrammatic representation of a lamp circuit employing the switch.

A sealed envelope i has mounted on a stem press or pinch 2 within it two supports 3 and 4, one (3) carrying a fixed contact 5 and the other (4) having attached to it one end of a U- shaped bimetallic strip 6. A bar "I carrying a movable contact 8 is mounted to be slidable in apertures in the two limbs of the U and has fixed thereto, on either side of the free limb of the U. a pair of collars or studs 9 and I acting as stops. The said collars or studs are spaced apart'sufliciently to give the desired amount of lost motion. The two supports 3 and 4 also serve as lead-in connections to the contacts H and H on base l3.

' other terminal l2 of the switch may be connected through the other filament or cathode l8 of the lamp and through a choke coil IE to the other supply terminal 20. A condenser 2| of, for example, 0.02 microfarad capacity should be connected across the switch terminals to improve operation.

In operation, when the supply is switched on a glow discharge takes place in the switch and the current flowing through the lamp filaments l5 and i8 heats them. The tree end of the bimetallic strip 6 is heated by the discharge and bends thus causing the limbs of the U to separate. The free limb engages the outer stop 10 on the slidable bar I and displaces the bar until the two contacts 8 and 5 engage. The glow then ceases.v As the bimetallic strip 6 cools, the free limb moves towards the fixed limb but the contacts 5 and 8 remain closed owing to slight welding. When the free limb reaches the inner stop 9 on the bar 1 force is applied which separates the contacts 5 and 8 suddenly. The voltage surge thus produced between the lamp electrodes 15 and it then causes the lamp to start. The lamp voltage which is now between the terminals of the switch is insuificient to restart a glow discharge and the slidable bar I therefore returns to its original position.

If the lamp it should fail to start, the full voltage is applied across the switch terminals, the glow starts, and the cycle above set forth is repeated.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A glow starter switch comprising a sealed envelope containing an ionizable medium, a, fixed contact electrode and a movable electrode spaced apart in said envelope for a glow discharge therebetween, said movable electrode comprising a bimetallic member and a movable contact mounted on said bimetallic member through a lost motion coupling, said bimetallic member being arranged to carry said movable contact into engagement with said fixed contact electrode when heated by the glow discharge to thereby extinguish the A thin wire It may be connected between the slidable bar I and the support-JV contact electrode and a movable electrode spaced apart in said envelope for a glow discharge therebetween, said movable electrode comprising a movable contact, a slide member carrying said movable contact and mounted for reciprocable movement to carry said movable contact into and out of engagement with said fixed contact electrode, and a bimetallic member connected by a lost motion coupling to said slide member and arranged to be heated by the glow discharge to effect actuation of said slide member.

3. A glow starter switch comprising a sealed envelope containing an ionizable medium, a fixed contact electrode and a movable electrode spaced apart in said envelope for a glow discharge therebetween, said movable electrode comprising a bimetallic member anchored at one end within said envelope, a slide member carrying a movable contact and connected to the free end of said bimetallic member by a lost motion'coupling, said bimetallic member being arranged to be heated by the glow discharge and to actuate said slide member to carry said movable contact into and out of engagement with said fixed contact electrode.

4. A glow starter switch comprising a sealed envelope containing an ionizable medium, a fixed contact electrode and a movable electrode spaced apart in said envelope for a glow discharge therebetween, said movable electrode comprising a bimetallic member anchored at one and within said envelope, a slidable bar-like member carrying a movable contact and extending through an aperture in the free end of said bimetallic member and provided with stop means on either side of said free end of the bimetallic member whereby to afford a lost motion coupling, said bimetallic member being arranged to be heated by the glow discharge to actuate said slide member to carry said movable contact into and out of engagement with said fixed contact electrode.

5. A glow starter switch comprising a sealed envelope containing an ionizable medium, a fixed contact electrode and a movable electrode spaced apart in said envelope for a, glow discharge there- .between, said movable electrode comprising a Ushaped bimetallic strip anchored at one end in said envelope, a bar-like member carrying a movable contact and mounted to be slidable in apertures in the ends of said bimetallic strip and provided with stop means on either side of the free end of said bimetallic strip whereby to afiord a lost motion coupling, said bimetallic strip being arranged to be heated by the glow discharge to actuate said bar-like member to carry said mov able contact into and out of engagement with said fixed contact electrode.

SIDNEY HOWARD NOBLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,809,299 Hodgkins' June 9, 1931 2,217,488 Mahuke Oct. 8, 1940 2,251,278 Hays, Jr., et a]. Aug. 5, 1941 2,329,134 Peters Sept. 7, 1943 

